Infrared reflective air-in-line sensor system

ABSTRACT

Air-in-line sensor systems and methods of using same are provided. In a general embodiment, the present disclosure provides an adapter including first and second cylindrical portions defining a fluid flow channel, the first cylindrical portion comprising two adjacent wedge-shaped protrusions. Each wedge-shaped protrusion is infrared transmittive and defines an outer surface and an inner surface. In another embodiment, an air-in-line sensor device includes a tube and an infrared reflective sensor having an infrared light emitter and an infrared light detector. The infrared light emitter and the infrared light detector are positioned at or near an adapter so that an infrared light can be transmitted to the adapter and at least a portion of the infrared light reflected off the adapter can be detected by the infrared light detector.

BACKGROUND

The present disclosure generally relates to health and nutrition. Morespecifically, the present disclosure relates to devices and methods fordetecting air in the tubing set of fluid pump systems.

The delivery of nutritional compositions to mammals, such as humanpatients, that cannot orally ingest food or other forms of nutrition isoften of critical importance. For example, enteral bottles andcontainers having feeding tubes that deposit food directly into thegastrointestinal tract at a point below the mouth are often used tosustain life while a patient is unable, or refuses, to take food orally.Bottles and containers, feeding tubes and other artificial deliverysystems and routes can be used temporarily during the treatment of acutemedical conditions. For chronic medical conditions, such systems androutes can be used as part of a treatment regimen that lasts for theremainder of a patient's life. No matter the duration of use, thesedevices often provide the only means for feeding and, thus, nutrientsupply, for the patient.

The use of enteral feeding pumps, in conjunction with an enteral feedingtube set as part of an enteral feeding system, for the administering ofmedical fluids is also well known in the medical arts. The enteralfeeding tube set will typically include several long sections of tubing,connected to a centralized, shorter section of tubing that can beincorporated into a pumping device. One common concern with the enteralfeeding tube set is that it may contain air boluses (e.g., bubbles),that can cause bloating, pain or general discomfort during and/or afterfeedings.

SUMMARY

The present disclosure relates to air-in-line sensor systems and methodsof using the air-in-line sensor systems. In a general embodiment, thepresent disclosure provides an adapter device having first and secondcylindrical portions defining a fluid flow channel. The fluid flowchannel extends through both the first and second cylindrical portions.The first cylindrical portion includes two adjacent wedge-shapedprotrusions. In an embodiment, each wedge-shaped protrusion having atleast a portion that is infrared transmittive and each protrusiondefining an outer surface and an inner surface. The inner surfaces ofthe wedge-shaped protrusions may define a substantially triangularlyshaped recess.

In an embodiment, the adapter has an interior surface defining a hollowinterior that is so constructed and arranged to allow fluid to flowtherethrough. At least a portion of the interior surface may be flat andinfrared reflective.

In an embodiment, the adapter is manufactured from polypropylene.

In another embodiment, a cassette is provided and includes a rigidframe, a tube, and at least one adapter having first and secondcylindrical portions defining a fluid flow channel. The firstcylindrical portion includes two adjacent wedge-shaped protrusions. Inan embodiment, each wedge-shaped protrusion having at least a portionthat is infrared transmittive and each protrusion defining an outersurface and an inner surface. The inner surfaces of the wedge-shapedprotrusions may define a substantially triangularly shaped recess.

In an embodiment, the at least one adapter is located on a first end ofthe cassette.

In an embodiment, the first portion of the adapter is configured to matewith the tube. The second portion of the adapter may be configured tomate with a second tube.

In an embodiment, the cassette includes first and second adapters, thefirst adapter is located on a first end of the cassette and the secondadapter located on a second end of the cassette.

In yet another embodiment, a sensor system is provided and includes apumping device and a cassette removably attached to the pumping device.The pumping device includes at least one infrared reflective sensorhaving an infrared light emitter and an infrared detector. The cassetteincludes a tube and at least one adapter having first and secondcylindrical portions defining a fluid flow channel. In an embodiment,each wedge-shaped protrusion having at least a portion that is infraredtransmittive and each protrusion defining an outer surface and an innersurface. The inner surfaces of the wedge-shaped protrusions may define asubstantially triangularly shaped recess. The infrared reflective sensoris positioned so that an infrared light can be transmitted through theouter surface of a first wedge-shaped protrusion and at least a portionof the infrared light reflected off an inner surface of the firstcylindrical portion can be detected by the infrared detector.

In an embodiment, the pumping device is an enteral feeding pump.

In an embodiment, the infrared light emitter and the infrared detectorare positioned on the same side within the pumping device. In anotherembodiment two infrared sensors are provided, one on each end of thepumping device. The infrared light emitter and the infrared detector mayalso be located on a bottom, interior portion of the pumping device suchthat the infrared light emitter emits the infrared light in an upwarddirection. The at least one adapter may be located on an end of thecassette and is configured such that the first and second adjacentwedge-shaped protrusions are oriented downward to communicate with theinfrared light emitter and the infrared detector.

In still yet another embodiment, a method of detecting air in a tubingset for an enteral feeding system is provided. The method includes thesteps of providing a cassette having an adapter sealingly attached to anenteral feeding tube, and detecting air within the enteral feeding tube.The adapter includes first and second portions defining a fluid flowchannel. The first portion includes two adjacent wedge-shapedprotrusions, each wedge-shaped protrusion having at least a portion thatis infrared transmittive and each protrusion defining an outer surfaceand an inner surface. The detecting occurs by transmitting an infraredlight to the outer surface of the first wedge-shaped protrusion anddetecting an amount of reflected infrared light using a detector.

In an embodiment, the infrared light is transmitted through the outersurface of a first wedge-shaped protrusion, and the reflected infraredlight passes through the outer surface of a second wedge-shapedprotrusion.

In an embodiment, the method further includes inserting the cassetteinto a pumping device to administer an enteral feeding to a patient.

In an embodiment, the method further includes stopping an enteralfeeding cycle if air is detected in the enteral feeding tube.Alternatively, the method may include sounding an audible alarm if athreshold amount of air is detected in the enteral feeding tube.

An advantage of the present disclosure is to provide an improved in-linesensor for detecting air in a tubing set.

Another advantage of the present disclosure is to provide an improvedmethod for detecting air in a tubing set for enteral feeding.

Yet another advantage of the present disclosure is to provide animproved sensor for detecting air that is cost-effective.

Still another advantage of the present disclosure is to provide animproved sensor for detecting air that is simple to operate.

Another advantage of the present disclosure is to provide an adapterthat can be used to detect air in a tubing set for enteral feeding.

Yet another advantage of the present disclosure is to provide a cassettehaving an adapter that can be used to detect air in a tubing set forenteral feeding.

Additional features and advantages are described herein, and will beapparent from the following Detailed Description and the figures.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 shows light passing from a first medium to a second medium havinga higher index of refraction.

FIG. 2 shows light passing from a first medium to a second medium havinga lower index of refraction.

FIG. 3 shows total internal reflection of an incident light ray.

FIG. 4 shows an incident light ray having an angle that is lower thanthe critical angle.

FIG. 5 shows an incident light ray having an angle that is greater thanthe critical angle.

FIG. 6 shows a perspective view of a pumping device and cassette havingan air-in-line sensor system in accordance with an embodiment of thepresent disclosure.

FIG. 7 shows a perspective view of the pumping device and the cassetteof FIG. 6 with the cassette inserted into the pumping device inaccordance with an embodiment of the present disclosure.

FIG. 8 shows a perspective view of an adapter and an infrared sensorhaving an infrared light emitter and an infrared light detector inaccordance with an embodiment of the present disclosure.

FIG. 9 shows a perspective view of an adapter for use with anair-in-line sensor system in accordance with an embodiment of thepresent disclosure.

FIG. 10 shows a cross-sectional view of the adapter and infrared sensorof FIG. 8 along line 10-10 in accordance with an embodiment of thepresent disclosure.

DETAILED DESCRIPTION

Enteral feeding pumps are devices that control the timing and the amountof nutrition delivered to a patient during enteral feeding. Enteralfeeding is the administration of nutrient fluids to a patient who cannoteat via normal ingestion routes. Enteral administration typically occursthrough a set of tubes between a feeding sack and a catheter implantedto the patient. A disposable cassette typically carries at least aportion of the tubing so that spent tubing may be easily disposed of. Anenteral feeding pump is usually connected to the feeding sack with onetube from a first side and with another tube to the patient on a secondside.

Due to the nature of the enteral fluids, the administering process andother enteral feeding conditions, it may occur that an amount of air isadministered instead of feeding fluid, which can easily result indiscomfort or pain to the patient. A typical example of this issueoccurs when the nutrient food sack becomes empty. If the enteral pumpcontinues the administration, air is pumped through the tubing to thepatient instead of food.

The present disclosure is directed to a sensor system that is able tosense the presence of air instead of nutrient fluid in the tubes of theenteral feeding system. When the volume of the pumped air has reached aprogrammed threshold, an alarm may be sent to the user. The sensorsystem is also able to distinguish between a small air bubble and thepresence of the determined amount of air in the tube, thereby avoidingfalse alarms to the user.

The detection of the presence and amount of air in the tubing is basedon the total internal reflection (“TIR”) principle derived from Snell'sLaw and the Fresnel Equations, which specify the relative amount oflight reflected and transmitted by a surface. The Law and the Equationsdescribe the behavior of a beam of light when it passes the surfacebetween two media characterized by different refraction indices.

Snell's Law describes the physical principle when a ray of light passesfrom one medium to another. Specifically, Snell's Law states that theratio of the sine of the angle of incidence to the sine of the angle ofrefraction is constant. The constant is either equal to (i) the ratio ofphase velocities (“v”) in the two media, or (ii) the opposite ratio ofthe indices of refraction (“n”) of the two media. Thus, Snell's Law isrepresented graphically by FIG. 1, and may be summarized as follows:

$\begin{matrix}{\frac{\sin\;\vartheta_{i}}{\sin\;\vartheta_{o}} = {\frac{v_{i}}{v_{o}} = \frac{n_{i}}{n_{o}}}} & {{Equation}\mspace{14mu} 1}\end{matrix}$

In Equation 1, θ_(i), is the ray incidence angle, θ_(o) is the refractedangle, θ_(r) is the reflected angle, v_(i) and v_(o) are the phasevelocities of the two materials, and n_(i) and n_(o) are the refractionindexes of the two materials.

Based on the possible values of the out-going ray angle, the followinginequality, derived by Equation 1, shall be verified:

$\begin{matrix}{{\sin\;\vartheta_{o}} = {{\frac{n_{i}}{n_{o}}\sin\;\vartheta_{i}} \leq 1}} & {{Equation}\mspace{14mu} 2}\end{matrix}$

When light passes from a first medium to a second medium characterizedby an higher refraction index, the beam of light reduces its angle tothe normal at the surface of separation between the two media, asillustrated in FIG. 1. As is also shown in FIG. 1, an amount of partialreflection also occurs.

In another example, when light passes from a first medium to a secondmedium characterized by a lower refraction index, the beam of lightincreases its angle to the normal at the surface of separation betweenthe two media and an amount of partial reflection also occurs, asillustrated in FIG. 2. In this situation (where light passes from afirst medium to a second medium characterized by a lower refractionindex), when the ratio of the refraction indices is fixed and ≧1, thesine of the incoming angle can only assume the values satisfying thefollowing inequality:

$\begin{matrix}{{\sin\;\vartheta_{i}} \leq \frac{n_{o}}{n_{i}}} & {{Equation}\mspace{14mu} 3}\end{matrix}$

With respect to Equation 3, when

${{\sin\;\vartheta_{i}} < \frac{n_{o}}{n_{i}}},$both refraction and partial reflection will occur. When

${{\sin\;\vartheta_{i}} = \frac{n_{o}}{n_{i}}},{\vartheta_{o} = {\frac{\pi}{2}\mspace{14mu}{and}\mspace{14mu}\vartheta_{i}}}$is the critical angle.

When

${\sin\;\vartheta_{i}} > \frac{n_{o}}{n_{i}}$refraction cannot occur and TIR occurs.

By increasing the incidence angle, the refraction angle also increases,and approaches a point in which the refracted beam runs parallel to thesurface separating the two media. This incident angle is called the“critical angle.” Further, when increase of the incident angle cannotresult in refraction, TIR occurs instead, as illustrated in FIG. 3. Theword “total” is important because, in contrast to FIGS. 1 and 2, inwhich some amount of light is reflected and some is refracted, when TIRoccurs, all of the energy of the incident beam of light is reflectedback.

The critical angle, thus, is defined as the arc whose sin equates theratio between the refraction index of the outgoing ray and the incidentray. In terms of a mathematical equation, the critical angle is definedas follows:

$\begin{matrix}{{\arcsin\;\vartheta} = \frac{n_{o}}{n_{i}}} & {{Equation}\mspace{14mu} 4}\end{matrix}$

As an example, the critical angle from water to air is about 48.6° andis represented by θ_(c) in FIGS. 2 and 3. As shown in FIG. 2, θ_(i) islower than θ_(c) so partial reflection and refraction occur. As shown inFIG. 3, θ_(i) is greater than θ_(c) so TIR occurs. Thus, with the samecritical angle, which is related to the refraction index of the twomaterials, different incident angles cause different paths of theincident rays.

In another example, the incident angles remain the same but the natureof the second material changes, thus also changing the refraction index.As shown in FIG. 4, θ_(c1) is lower than θ_(i) so TIR occurs. As shownin FIG. 5, θ_(c2) is greater than θ_(i) so partial reflection andrefraction occurs. Thus, with the same incident angle, different amountsof light can be reflected, given the refraction index of the secondmaterial.

In other words, it is possible to distinguish different materialsmeasuring the amount of light received at the reflection surface of thefirst material. For example, assuming that food has a refraction indexsimilar to that of water and other effects of lower order such asscattering, ambient light, sticky food, etc. are not present or aremitigated, a TIR situation may be adopted to determine the present of,for example, air in the tubing of an enteral pump.

Accordingly, Snell's Law provides a method by which the refractionangles and the critical angles may be determined, given the incidenceangle and the refraction indices of the two media. Using the same data,the Fresnel Equations allow the relative amount of light reflected withrespect to the amount of light transmitted to be determined. Forexample, with reference to FIGS. 4 and 5, the Fresnel Equations canprovide the amount of light reflected and the amount of lighttransmitted. A precise determination of these values is importantbecause it can aid in clearly distinguishing, for example, the presenceof air or food in the tubing of an enteral pump.

Referring again to FIG. 1, the fraction of the incident power that isreflected is given by the reflectance (“R”) and the fraction that isrefracted is given by the transmittance (“T”). The calculations of R andT depend on the polarization of the incident ray. Considerings-polarized light (perpendicular to the plane of FIG. 1) and p-polarizedlight (in the plane of FIG. 1), the R and T coefficients are given bythe following:

$\begin{matrix}{R_{s} = {{\left( \frac{{n_{i}\cos\;\vartheta_{i}} - {n_{o}\cos\;\vartheta_{o}}}{{n_{i}\cos\;\vartheta_{i}} + {n_{o}\cos\;\vartheta_{o}}} \right)^{2}\mspace{14mu} T_{s}} = {1 - R_{s}}}} & {{Equation}\mspace{14mu} 5} \\{R_{p} = {{\left( \frac{{n_{i}\cos\;\vartheta_{o}} - {n_{o}\cos\;\vartheta_{i}}}{{n_{i}\cos\;\vartheta_{o}} + {n_{o}\cos\;\vartheta_{i}}} \right)^{2}\mspace{14mu} T_{p}} = {1 - R_{p}}}} & {{Equation}\mspace{14mu} 6}\end{matrix}$

If the incident light is unpolarized, the reflection coefficient is:

$R = \frac{\left( {R_{s} + R_{p}} \right)}{2}$

Applicants have now found that properly choosing a material for thefirst medium, the geometry around the surface between the two media, theincident angle, and the way to generate and sense the light, it ispossible to design a sensor able to distinguish if the second medium is,for example, air or fluid. For example, if the first medium has arefraction index of 1.5, the refraction index of air is 1, and that ofwater is 1.33, any incidence angle between about 42° and about 62° willallow a user to determine whether the second medium is air or water byreading the amount of light reflected. This will be advantageous when,for example, the first medium is the tubing (or a like structure) of acassette for an enteral feeding.

As illustrated in FIGS. 6-7, in an embodiment, the present disclosureprovides an air-in-line sensor system 10 including a cassette 20removably attachable to a pumping device 30. Cassette 20 can include ahousing or support structure having any suitable shape such as the oneshown in FIG. 6. Cassette 20 can be designed to be inserted partially orwholly within pumping device 30, as seen in FIG. 7. The design ofcassette 20 can help in loading an enteral feeding tube set into pumpingdevice 30 without having to route/guide the tubes or stretch the tubesfrom the tube set over a rotor (e.g., part of a peristaltic pump)contained within pumping device 30. Non-limiting examples of alternativecassette configurations are described in U.S. Pat. Nos. D504,506,D505,199, D455,489, D501,924 and D507,647, which are incorporated hereinby reference. Cassette 20 can be made from any suitable rigid,semi-rigid or flexible material. Cassette 20 can also be designed suchthat it can be inserted into pumping device 30 only one way.

Cassette 20 includes tube 22, which can be flexible and have portionsthat are rigid or semi-rigid. Tube 22 can be a feeding tube and beconstructed and arranged to be incorporated with the rotors of a pump(e.g. peristaltic pump) in pumping device 30.

Pumping device 30 can be an enteral feeding pump. The pump containedwithin pumping device 30 can be a peristaltic pump. Non-limitingexamples of pumping devices are described in U.S. Pat. No. 6,659,976,which is incorporated herein by reference. As shown by FIG. 7, pumpingdevice 30 can include a monitor/information screen 36 and a control pad38 for operating pumping device 30. Monitor/information screen 36 andcontrol pad 38 can also be used in conjunction with the air-in-linesensor system in embodiments of the present disclosure. Pumping device30 can further include a power button 32 and a release mechanism 34 forreleasing cassette 20 from pumping device 30.

Pumping device 30 can also include one or more infrared sensors 40 and50. In an embodiment, pumping device 30 includes one infrared sensor 40that is located on an inlet side of pumping device 30 where cassette 20is connected to a solution bag, as shown in FIG. 6. Infrared sensors 40,50 include infrared reflective light emitters 42 and 52, respectively.Infrared sensors 40, 50 further include infrared detectors 44 and 54,respectively, positioned as part of the air-in-line sensor system 10within an inner section of pumping device 30. Infrared light emitters42, 52 can be a light emitting diode. Infrared light detectors 44, 54can be a photodiode or a phototransistor. Infrared sensors 40 and 50 arelocated in pumping device 30 to avoid wear and tear or damage toinfrared sensors 40 and 50 due to handling by a user. This is importantbecause the most expensive element of the present systems are infraredsensors 40 and 50.

Infrared sensors 40, 50 can be any suitable infrared sensor having aninfrared emitting device 42 and a detection device 44, as shown by FIG.8. Non-limiting examples of infrared sensors 40, 50 include infraredsensors developed under the QRD series by Fairchild Semiconductor.Infrared light emitters 42, 52 and infrared detectors 44, 54 can besupported or positioned on any suitable support (e.g. within pumpingdevice 30).

Cassette 20 further includes tube 22 and at least one adapter 60 as partof the air-in-line sensor system, and as shown in FIG. 6. When cassette20 is inserted into pumping device 30, infrared reflective lightemitters 42, 52 and infrared detectors 44, 54 can be positioned to layside-by-side and adjacent to adapter 60, as illustrated in FIG. 8. Inthis manner, although infrared sensors 40, 50 are illustrated in FIG. 6as being located on a top, interior portion of pumping device 30, so asto be located on a top portion of cassette 20, infrared sensors 40, 50may also be located on a bottom, interior portion of pumping device 30,so as to be located on a bottom portion of cassette 20 when cassette 20is loaded into pumping device 30, as shown in FIG. 7. In an embodiment,infrared sensors 40, 50 are located on a bottom, interior portion ofpumping device 30 so as to emit infrared light from infrared reflectivelight emitters 42, 52 in an upward direction to contact a portion ofadapter 60, which reflects (and/or refracts) the infrared light in adownward direction to be received by infrared detectors 44, 54.

As is most clearly shown in FIG. 9, adapter 60 has a first portion 62and a second portion 64 separated by an intermediate third portion 66.First portion 62 includes two wedge-shaped projections 68 that extendfrom the natural surface of first portion 62. In other words, asillustrated in FIG. 9, adapter 60 is substantially cylindrically shaped(having a natural cylindrically shaped surface) and wedge-shapedprojections 68 extend from what would be a cylindrically shaped surfaceunderneath wedge-shaped projections 68 if wedge-shaped projections 68were not included on adapter 60. Although illustrated as substantiallycylindrical in FIG. 9, the skilled artisan will appreciate that adapter60 may have any shape known in the art that allows adapter 60 tofunction as a tubing adapter.

Wedge-shaped projections 68 are substantially triangularly shapeddefining a substantially triangularly shaped recess 70 therebetween.Flat portions of wedge-shaped projections 68 opposite recess 70 may beused as surfaces for transmission of incident infrared light rays andfor reflected infrared light rays, as shown in FIG. 10. In this manner,and in an embodiment, infrared reflective light emitters 42, 52 can emitinfrared light, which may be focused by a lens (e.g., prism) 78 prior totransmission through the material of adapter 60 to an interior wall 72of adapter 60, which serves as the media separation surface betweenadapter 60 and the contents flowing through adapter 60 and tube 22 ofthe enteral feeding system (e.g., nutritional composition, water, air,etc.). When the infrared light hits media separation surface 72, theincident infrared light ray is reflected and/or refracted. Any reflectedlight is reflected through adapter 60, which may be focused by a lens(e.g., prism) 80 prior to reception of the infrared light rays byinfrared detectors 44, 54. For ease and accuracy of measurement ofreflected and/or refracted infrared light, interior wall 72 of adapter60 should be substantially perpendicular to a line running through themiddle of recess 70 and bisecting adapter 60 into two equal halves. Aremaining portion of the interior wall of adapter 60 can besubstantially cylindrical for ease of passing fluid therethrough.

With respect to prisms 78, 80, the skilled artisan will appreciate thatalternative embodiments are provided in the present disclosure that donot include prisms 78, 80. For example, in an embodiment, prisms 78, 80of FIG. 10 are not included. Instead, the relative angles of theinfrared reflective light emitters 42, 52 and infrared detectors 44, 54may be increased. By removing prisms 78, 80 and increasing the relativeangles of infrared reflective light emitters 42, 52 and infrareddetectors 44, 54, it is possible to manufacture a cheaper infraredsensor 40, 50 and to avoid any possible issues that may arise from useof prisms 78, 80 (e.g., imperfections that cause reflection orrefraction issues).

In an embodiment, wedge-shaped projections 68 may have a sloped portion68 a toward a front end of adapter 60, as shown in FIG. 9. Slopedportions 68 a of wedge-shaped projections 68 may assist a user inpress-fitting tube 22 around adapter 68 for use in pumping fluidsthrough adapter 60. Sloped portions 68 a may also serve as a stoppingmeans to prevent tube 22 from extending the entire length of firstportion 62. In other words, one advantage of the use of present adapter60 is that infrared light does not need to travel through tube 22 andadapter 60 to arrive at media separation surface 72. Instead, infraredlight simply has to pass through adapter 60 to arrive at mediaseparation surface 72.

Second portion 64 of adapter 60 is so constructed and arranged to beattached to a tubing portion 74 that is connected to a nutritionalcomposition supply bag, and/or a tubing portion 76 that is connected toa patient for fluid delivery. Second portion 64 may be attached totubing portions 74, 76 by any means known in the art including, but notlimited to, press-fitting, bonding, welding, adhesives, etc. In anembodiment, second portion 64 is bonded to tubing portions 74, 76.Second portion 64 may have a diameter that is smaller than, the same as,or greater than first portion 62. In an embodiment, second portion 64has a diameter that is greater than first portion 62.

Third portion 66 is located intermediate first portion 62 and secondportion 64, and has a diameter that is greater than first portion 62 andsecond portion 64. Third portion 66 is useful for proper alignment andplacement of adapter 60 in cassette 20. As shown in FIG. 6, adapter 60is located on outer edges of cassette 20 and may be placed therein byinserting first portion 62 of adapter 60 into a similarly sized hole incassette 20 and press-fitting first portion 62 of adapter 60 into tube22. In this manner, third portion 66 prevents adapter 60 from beinginserted too far into an interior portion of cassette 20 and helps tokeep tubing 22, 74, 76 in place during delivery of fluids to a patient.

As is shown in FIG. 9, and as discussed in part above, adapter 60 has aspecial geometry including at least wedge-shaped projections 68 andinterior wall 72 that has been adopted to take advantage of the physicalprinciples used to detect air in the tubing set and to solvemold-ability issues. Not only is the geometry of adapter 60advantageous, however, but the material used to manufacture adapter 60is also beneficial. In an embodiment, adapter 60 may be manufacturedfrom a food grade polymer such as, but not limited to polypropylene,Teflon®, methylmethacrylate-acrylonitrile-butadiene-styrene copolymer(“MABS”), etc. In an embodiment, adapter 60 is made of polypropylene,which is well-suited for use with foods and has a low adhesioncoefficient. By preventing food from sticking to an interior of adapter60, a greater amount of infrared light is allowed to pass therethrough,and materials having increased viscosities may also be used.

Referring now to FIG. 10, infrared reflective light emitter 42, 52 sendsa beam of light to a section of adapter 60, which is attached tocassette 20 and receives the nutritional composition from the bag fromone side and interfaces with the patient on the other. The food or theair passing through adapter 60 and, hence, tube 22, will cause adifferent amount of light be transferred to detector 44, 54 placed atthe reflection angle. An LED driving circuit and a photosensor amplifierand filter circuits will send an output to an analog to digitalconverter, which will allow a pump microcontroller to supply the optimalamount of infrared light and to determine the presence of air in adapter60 and, hence, tube 22, instead of nutrient fluid.

As mentioned briefly above, fluid can flow through tube 22 in thedirection from the bag to the patient as shown in FIG. 6. Tube 22extends within the bound of cassette 20. Adapter 60 is used to join tube22 with tube 74 that attaches to the bag containing a nutritionalcomposition source. Similarly, adapter 60 is used to join tube 22 withtube 76 that attaches to the person receiving the nutritionalcomposition. In this manner, tube 22 may be press fit over first portion62 of adapter 60 until tube 22 is sealingly joined to adapter 60. In anembodiment wherein two adapters 60 are present, tube 22 is joined toadapters 60 at both ends of cassette 20.

Infrared sensors 40 and 50 can be positioned on either side of a pump(not shown) within pumping device 30. For example, the pump can belocated at a central location of pumping device 30 and would interactwith tube 22 located at a central cut-out portion 28 of cassette 20.Accordingly, infrared sensor 40 may be placed upstream of the pump at alocation to interact with adapter 60 located upstream of the pump (e.g.,receive a nutritional composition from a container or bag). Similarly,infrared sensor 50 may be placed downstream of the pump at a location tointeract with adapter 60 located downstream of the pump (e.g., sending anutritional composition to the patient). Similarly, both infraredsensors 40, 50 may be included in an embodiment, one infrared sensor 40may be included in another embodiment, or one infrared sensor 50 may beincluded in yet another embodiment.

During operation, the pump (not shown) within pumping device 30 locatednear portion 28 pumps the nutritional composition from a bag throughcassette 20 via tube 74, a first adapter 60, tube 22, a second adapter60, and tube 76 to a patient. If there is no air detected in the linebetween the bag and the pump or the pump and the patient, pumping device30 will continue to deliver a feeding to the patient. However, if air isdetected by sensor system 10 at either first or second adapters 60,infrared sensors 40, 50 send this information to a central processingunit of pumping device 30, which is able to use stored information andparameters to determine how much air has been sensed in the line betweenthe bag and the patient. If a predetermined threshold of an amount ofair in the tubing is detected, air-in-line sensor system 10 may enter asafe mode where an alarm is sounded to warn the patient, or the pumpingdevice 30 automatically shuts off to cease delivery of the fluid, etc.

In another embodiment, pumping device 30 may have a clear window (notshown) located on an interior surface. The window can be made, forexample, from a molded, plastic and can serve as a barrier betweeninfrared sensors 40, 50 and any exterior source of liquid. The windowmay be chemically doped and should be an infrared transparent surface sothat infrared light can pass though the window. The purpose of thewindow is to prevent liquid from entering an interior portion of pumpingdevice 30 that contains the electrical and mechanical components. Forexample, during cleaning of pumping device 30, it is desirable toprevent water, soap and/or cleaning chemicals from leaking into pumpingdevice 30 and damaging or destroying any electrical or mechanicalcomponents.

In another embodiment, the infrared light emitted from an infrared lightemitter may be either pulsed or continuous. An advantage of providing acontinuous emission of infrared light includes a constant monitoring(e.g., detecting) of any fluids being pumped through a cassette andprovided to a patient. In this manner, continuous detection reduces anypossibility of failing to detect a problematic pumping condition (e.g.,air bubbles). There are also several advantages, however, to providingan embodiment wherein the infrared light is pulsed. For example, pulsedinfrared light detection provides for ambient light rejectioncapability, stability of the amount of infrared emitted light (e.g.,emitter does not over-heat), longer life of the emitter, which will notdegrade its optical characteristics for aging, and reduced powerconsumption. As such, the skilled artisan will appreciate that thepresently disclosed pumps and pumping systems may include either pulsedor continuous infrared light emissions.

In an alternative embodiment, the present disclosure provides a cassettethat incorporates an infrared reflective sensor including an infraredlight emitter and an infrared detector. In this regard, the pumpingdevice does not house the infrared reflective sensor. However, theinfrared reflective sensor on the cassette can be constructed andarranged to interact with the pumping device so that the results of theinfrared reflective sensor can be displayed on a monitor of the pumpingdevice.

In yet another embodiment, the present disclosure provides a method ofdetecting air in a tubing for an enteral feeding system. The methodcomprises providing an air-in-line sensing system including a feedingtube and an infrared reflective sensor including an infrared lightemitter and an infrared light detector. The feeding tube can beincorporated as part of a cassette that can be attached to a pumpingdevice of the enteral feeding system.

The method further comprises detecting air within the feeding tube bytransmitting an infrared light toward an adapter in fluid communicationwith the feeding tube and detecting reflected infrared light using theinfrared detector, for example, based on an amount of light reflectedand/or refracted. If air is detected in the feeding tube, the pumpingdevice can be stopped, for example, during an enteral feeding cycle.

Applicants have combined a unique adapter with an air-in-line sensorsystem to be able to determine whether the adapter and/or tubing of anenteral feeding system contains a fluid or air. Attempts to adopt theabove physical principles to implement such an air-in-line sensor for anenteral feeding pump was not easily accomplished, however. In thismanner, Applicants were cognizant of the following potentialcomplications: (i) the physical dimensions of the pump did not allow alarge reflection surface; (ii) the costs of the sensor were not to limitits commercialization; (iii) the light source could not be a collimatedX-ray, therefore, secondary level optical phenomenon was considered;(iv) not all of the light in the pump was reflected or refracted, andabsorption and scattering of light was also considered; (v) ambientlight can affect the photosensor reading; (vi) some foods show highviscosity and are not homogeneous, which can create tubes clearanceissues; (vii) most of the food materials with a high degree of clearancehad very low refraction indices, which resulted in bonding and slipperyproblems interfacing with the tubes; (viii) consistent mold-ability ofoptical parts with lens was difficult; (ix) spread in theopto/electrical parameters of the optical components was typically high;and (x) aging of the optical components could effect sensor sensibility.

By working through the difficulties in achieving the present air-in-linesensors, Applicants were able to achieve an improved air-in-line sensorthat provides many advantages over prior art air sensors. For example,the present air-in-line sensors are a low cost, reliable solution thatworks in several operating environments. The present air-in-line sensorscontinue to work regardless of whether the tube is occluded, and do notrequire any plate against which light is reflected or absorbed. Theair-in-line sensors of the present disclosure also operate with largevarieties of foods and are immune against aging and associated problemstypically found with similar optical systems.

It should be understood that various changes and modifications to thepresently preferred embodiments described herein will be apparent tothose skilled in the art. Such changes and modifications can be madewithout departing from the spirit and scope of the present subjectmatter and without diminishing its intended advantages. It is thereforeintended that such changes and modifications be covered by the appendedclaims.

The invention is claimed as follows:
 1. An adapter device configured tojoin one tube with another tube, the adapter device comprising: firstand second cylindrical portions defining a fluid flow channel, the firstcylindrical portion comprising two adjacent wedge-shaped protrusions,each wedge-shaped protrusion having at least a portion that is infraredtransmissive and each protrusion defining an outer surface and an innersurface, wherein the two wedge-shaped protrusions are substantiallytriangularly shaped defining a substantially triangularly shaped recesstherebetween, and an interior wall of the first cylindrical portionserves as a media separation surface between the adapter device andcontents flowing through the adapter device, wherein the interior wallof the first cylindrical portion is substantially perpendicular to aline running through a middle of the recess and bisecting the adapterdevice into two equal halves.
 2. The adapter of claim 1, wherein thefluid flow channel extends through both first and second cylindricalportions.
 3. The adapter of claim 2, wherein a portion of the interiorwall is flat and is infrared reflective.
 4. The adapter of claim 1,wherein the adapter is manufactured from polypropylene.
 5. A cassettecomprising: a rigid frame; a tube; and at least one adapter deviceconfigured to join the tube with another tube that is not a part of thecassette, the at least one adapter device comprising first and secondcylindrical portions defining a fluid flow channel, the firstcylindrical portion comprising two adjacent wedge-shaped protrusions,each wedge-shaped protrusion having at least a portion that is infraredtransmissive and each protrusion defining an outer surface and an innersurface, wherein the two wedge-shaped protrusions are substantiallytriangularly shaped defining a substantially triangularly shaped recesstherebetween, and an interior wall of the first cylindrical portionserves as a media separation surface between the adapter device andcontents flowing through the adapter device, wherein the interior wallof the first cylindrical portion is substantially perpendicular to aline running through a middle of the recess and bisecting the adapterdevice into two equal halves.
 6. The cassette of claim 5, wherein the atleast one adapter is located on an end of the cassette.
 7. The cassetteof claim 5, wherein the first portion of at least one of the at leastone adapter device is constructed and arranged to mate with the tube. 8.The cassette of claim 5, wherein the second portion of at least one ofthe at least one adapter device is constructed and arranged to mate witha second tube.
 9. The cassette of claim 5, the at least one adapterdevice comprising first and second adapters, the first adapter locatedon a first end of the cassette and the second adapter located on asecond end of the cassette.